最近幾年，行動裝置受到越來越多人的青睞與使用，例如筆記型電腦及智慧型手機，人們的生活也隨著受到相當程度的影響。無線隨意網路是一個非常適合且有效率的網路系統，在沒有無線接取熱點及基地台的支援下，它使這些行動裝置能互相交換資料與溝通。無線隨意網路並不只侷限在單一點對點或多點廣播的通訊方式，在實際的應用上依然存在著多對多的通訊方式需求，此類可稱之為群組通訊。雖然，有許多研究在群組通訊方面發展，然而直到最近群組如何在無線隨意網路中組成，依舊缺乏深入的探討。
另一方面，車載應用系統也受到科技發展的影響，車間通訊成為智慧型傳輸系統中不可或缺的一部份。對於車載隨意網路，車間通訊是一項很重要的研究議題，因為它提供車載器具間的通訊，在車載隨意網路中，互相交換交通資訊，可以提高交通的安全性。為了確保這些交換的訊息，能夠有效率且安全的傳遞，安全防護成為車載隨意網路的關鍵議題。傳統的安全機制都非常倚賴集中式的基礎建設，以進行安控，如密鑰的指定與管理，但這並不適合車載隨意網路，因為它具有高移動性及多跳式的連接。部分研究提出，車輛需與路邊固定裝置連接，但此卻需要龐大的建設成本，路邊固定裝置也無法涵蓋所有道路。
因為無線通訊的方式是廣播，這使得在無線隨意網路中的行動裝置，都能接收到通訊的訊息，這對敏感的資料，就產生的安全性的重要議題。所以，在無線隨意網路中，對於車間通訊及群組通訊如何產生群組並且確保通訊的安全，是非常必要且值得努力研究改善的。
本篇論文對於無集中式基礎建設及路邊固定裝置可利用的分散式車間通訊，提出一個於車載隨意網路動態建立安全通訊的方法，以進行密鑰的建立，經由綜效分析與模擬，本論文提出的方法，在車輛相對速度餘時速240公里時，仍良好運作。針對無線隨意網路中的群組通訊，提出一個基於虛擬子網路模式建構於無線隨意網路之安全群組通訊，在論文中，提出以虛擬子網路的方式，使群組得以形成，並且同時產生群組通訊的密鑰，以保護將群組通訊的資料安全。經由分析與實驗，顯示出本文的方法可以同時達到效率與安全性的需求。

Recently, more and more people have begun using mobile devices such as PDAs, notebooks and intelligent cell phones. Our lives have been deeply affected by such devices. MANET, a mobile ad hoc network, is an effective networking system facilitating data exchange between these mobile devices, without the support of wirelesses access points and base stations. MANET is not restricted to unicast or multicast communication, but can also be “many-to-many” transmissions, which can be treated as a group communication. Until recently, however, the way in which such groups are formed has not drawn much attention.
Vehicular applications also affects by the technological development, inter-vehicle communication (IVC) emerges as an indispensable part of intelligent transportation system (ITS). The IVC is an important research topic and works based on vehicular ad hoc networking (VANET), and provides communications among vehicles. With the interchange of traffic information, the wide applications of VANET help to improve driving safety. To ensure that messages can be delivered effectively and validly, the security in VANET becomes a critical issue. Due to VANET's high mobility and ad hoc links, conventional security systems are not suitable, which rely heavily on centralized infrastructure to perform security operations such as key assignment and management. Some researches proposed that vehicles should be connected to fixed devices such as road side units (RSUs), but the need to deploy a large number of expensive RSUs in a specific area.
Apparently, the communication manner in wireless networks is a broadcast and a certain amount of devices can receive transmitted messages, the risk of unsecured, sensitive information being intercepted by unintended recipients is a real concern. Consequently, efforts to ensure the security of vehicular communication and group communication in ad hoc networks are essential.
My dissertation focuses on the decentralized IVC without fixed infrastructure and proposes a method for Dynamic Establishment of Secure Communications in VANET (DESCV), which works well for VANET in particular the communication key management when centralistic infrastructure or RSU is not available. Through synergy analysis and simulations demonstrate that DESCV performs well in providing secure communications among vehicles traveling at a relative velocity as high as 240 km/h. For the secure group communication, a virtual subnet based group construction over ad hoc networks also presents in this dissertation. With the model, the composition of groups is established so as the forming of group keys. The verifications indicate that this approach can completely satisfies the needs for both security and efficiency.

摘要…………………………………………………………I
誌謝…………………………………………………………V
TABLE OF CONTENTS………………………………………VI
LIST OF TABLES………………………………… ……VIII
LIST OF FIGURES…………………………………………IX
Chapter 1 Introduction ………………………………1
1.1 Communication of Vehicles…………………1
1.2 Secure Group Communication… ……………5
1.3 The Outline of Dissertation………………9
Chapter 2 Related Works ……………………………11
2.1 Original Knapsack Cryptosystem…… ……11
2.2 Virtual Local Area Network.………………15
2.3 Secure Group Communication……………… 19
2.3.1 Secure Group Communication in Wired Network…19
2.3.2 Secure Group Communication in Wireless Network. .20
2.3.3 Group Key Distribution Protocol…………21
Chapter 3 Secure Vehicle Ad Hoc Networks………25
3.1 DESCV Cryptosystem in VANET ……………25
3.2 DESCV Procedure………………………………30
Chapter 4 Synergy Analysis of DESCV… …………35
4.1 Security Analysis………… ……………35
4.2 Throughput Evaluation……… …………38
Chapter 5 Constructing Groups in MANET…………45
5.1 Initiation Stage……… ……… … ………47
5.2 Creation Stage……………… ………………48
5.3 Maintain Mechanism…………… ……………50
5.4 Transmission Mechanism………… …………51
Chapter 6 Group Key Agreement in Virtual Subnet …60
Chapter 7 Analysis and Simulation…… …………67
7.1 Analysis………………………………………67
7.2 Simulation……………………………………68
Chapter 8 Conclusion and Future Work..........72
Reference ………………………… ……………………74
自述…………………………………… …………………79

[1] J. M. McQuillan and D. C. Walden, “The ARPA Network Design Decisions,” in Computes Network, vol. 1, August 1977, pp. 243-289.
[2] J. Jubin and J.D. Tornow, “The DARPA Packet Radio Network Protocols,” Proceeding of the IEEE, Vol.75, no. 1, Jan. a987, pp. 21-32.
[3] Rajaravivarma, V.; “Virtual local area network technology and applications,” Proceeding of the Twenty-Ninth Southeastern Symposium on , 9-11 March 1997, pp:49 – 52.
[4] N. Kavak, “Data Communications in ATM Networks,” IEEE Network, vol.9, no.3, May/June 1995.
[5] A. Gupta and D. Ferrari, “Resource Partitioning for Real-time Communication,” IEEE/ACM Trans. on Networking,Vol. 3, No. 5, Oct 1995, pp. 501–518.
[6] E. Shi and A. Perrig, “Designing secure sensor networks,” Wireless Communications, IEEE Volume 11, Issue 6, Dec. 2004, pp.38 – 43.
[7] I. Stojmenovic, “Geocasting with guaranteed delivery in sensor networks,” Wireless Communications, IEEE Volume 11, Issue 6, Dec. 2004, pp.29 – 37.
[8] N. B. Salem and J.-P. Hubaux, “Securing wireless mesh networks,” Wireless Communications, IEEE Volume 13, Issue 2, Apr. 2006, pp.50 – 55.
[9] Y.-M. Huang, H.-Y. Lin and T.-I. Wang, “Inter-Cluster Routing Authentication for Ad Hoc Networks by a Hierarchical Key Scheme,” Journal of Computer Science and Technology, Vol.21, No.6, Nov. 2006 pp.997-1011.
[10] IEEE Std 802.1Q, 2003 Edition. IEEE standards for local and metropolitan area networks. Virtual bridged local area networks.
[11] W. Diffie and M. Hellman, “New directions in cryptography,” IEEE Transactions on Information Theory, Nov. 1976, pp 644-654.
[12] Ingemar Ingemarsson, Donald Tang and C. Wong. “A conference key distribution system.” IEEE transactions on Information Theory, September 1982, pp. 714-720.
[13] Yi Mu, Yuliang Zheng and Yan-Xia Lin. “Quantum conference key distribution systems.” Techical Report 94-96,University of Wollongong, NSW, Australia, 1994.
[14] M. Steiner, G. Tsudik, and M. Waidner. “Diffie-Hellman key distribution extended to group communication.” In ACM CCS 1996, pp. 31-37.
[15] S. Zhu, S. Xu, S. Setia, and S. Jajodia. “Establishing pair-wise keys for secure communication in ad-hoc networks: A probabilistic approach.” IEEE International Conference on Network Protocols, 2003, pp. 326-335.
[16] S. Basagni, K. Herrin, E. Rosti, and D. Bruschi. Secure pebblenets. ACM Symposium on Mobile Ad Hoc Networking and Computing (MobiHoc), 2001, pp.156-163.
[17] N. Asokan and P. Ginzboorg. “Key agreement in ad hoc networks.” In Computer Comm., volume 23, 2000, pp. 1627–1637.
[18] X. Li, Y. Yang, M. Gouda, and S. Lam. Batch rekeying for secure group communications. 10th international conference on World Wide Web, 2001, pp.525-534.
[19] C. Wong and S. Lam. Keystone. “A group key management service.” International Conference on Telecommunications, May 2000.
[20] Y. Yang, X. Li, X. Zhang, and S. Lam. “Reliable group rekey-ing: a performance analysis.” In SIGCOMM 2001.
[21] X. Zhang, S. Lam, and D.-Y. Lee. “Group rekeying with limited unicast recovery.” Comput. Networks, 44(6), 2004.
[22] X. Zhang, S. Lam, D.-Y. Lee, and Y. Yang. “Protocol design for scalable and reliable group rekeying.” ToN, 11(6), 2003.
[23] S. Yi and R. Kraverts. “Key management in heterogeneous ad hoc wireless networks.” 10th IEEE International Conference on Network Protocols, 2002, pp. 202 - 205.
[24] J. Kong, P. Zerfos, H. Luo, S. Lu, and L. Zhang. “Providing robust and ubiquitous security support for mobile ad-hoc networks.” 10th IEEE International Conference on Network Protocols, 2001, pp 251.
[25] J.P. Hubaux, L. Buttyan, and S. Capkun. “The quest for security in mobile ad hoc networks.” In ACM MobiHoc, 2001.
[26] J. E. wieselthier, G.D. Nguyen, and A. Ephremides, “Algorithms for Energy-efficient Multicasting in Static Ad Hoc Wireless Network,” Mobile Networks and Applications(MONET), 6-3,June 2001, PP. 251-263.
[27] C. E. Perkins and E. M. Royer, "Ad-hoc On-Demand Distance Vector
Routing," Internet Engineering Task Force, RFC 3561, July 2003.
[28] D. Johnson, D. A. Maltz and Y. C. Hu, "The Dynamic Source Routing
Protocol (DSR) for Mobile Ad Hoc Networks for IPv4," RFC 4728 IETF
Mobile Ad Hoc Networks Working Group, Feb. 2007.
[29] L. Wischhof, A. Ebner, H. Rohling, "Information Dissemination in Self-Organizing Intervehicle Networks," IEEE Transactions on Intelligent Transportation Systems, Mar. 2005, pp. 90-101.
[30] J. Zhang, Q. Zhang, B. Li, X. Luo, and W. Zhu, "Energy Efficient Routing in Mobile Ad-hoc Networks: Mobility Assisted Case," IEEE Transaction on Vehicular Technology, Vol. 55, Issue 1, Jan. 2006, pp. 369-379.
[31] K. I. Kim and S. H. Kim, "A novel overlay multicast protocol in mobile ad hoc networks: design and evaluation," IEEE Transaction on Vehicular Technology, Vol. 54, Issue 6, Nov. 2005, pp. 2094-2101.
[32] L. Lao and J. H. Cui, "Reducing multicast traffic load for cellular networks using ad hoc networks," IEEE Transaction on Vehicular Technology, vol. 55, Issue 3, May. 2005, pp. 822-830.
[33] A. Mishra, K. Nadkarni and A. Patcha, "Intrusion detection in wireless ad hoc networks," IEEE Wireless Communications, vol. 11, Issue 1, Feb. 2004, pp. 48-60.
[34] R. Rivest, A. Shamir and L. Adleman, "A Method for Obtaining Digital Signatures and Public-Key Cryptosystems," Communication of the ACM, vol. 21, no. 2, Feb. 1978, pp. 120-126.
[35] R. Merkle and M. E. Hellman, "Hiding information and signatures in trapdoor knapsack," IEEE Trans. Inform. Theory, vol. 24, Issue 5, Sep. 1978, pp. 525-530.
[36] A. Shamir, "A polynomial-time algorithm for breaking the basic Merkle-Hellman cryptosystem," IEEE Trans. Inform. Theory, vol. 30, Issue 5, pp. 699-704, Sep. 1984.
[37] J. C. Lagarias and A. M. Odlyzko, "Solving low-density subset sum problems," 24th Annu. Symp. Foundations Comput. Sci, 1983, pp. 1-10.
[38] C. S. Laih, J. Y. Lee, L. Harn and Y. K, Su, "Linearly shift knapsack public-key cryptosystem," IEEE Journal on Selected Areas in Communications, vol. 7, Issue 4, May. 1989, pp. 534-539.
[39] Y. M. Huang, H. Y. Lin and T. I. Wang, "Inter-Cluster Routing Authentication for Ad Hoc Networks by a Hierarchical Key Scheme," Journal of Computer Science and Technology, vol. 21, no.6, Nov. 2006, pp. 997-1011.
[40] S. Zhu, S. Setia, S. Jajodia and P. Ning, "An interleaved hop-by-hop authentication scheme for filtering of injected false data in sensor networks," IEEE Symposium on Security and Privacy, May. 2004, pp. 259-271.
[41] F. Ye, H. Luo, S. Lu and L. Zhang, "Statistical en-route filtering of injected false data in sensor networks," Twenty-third Annual Joint Conference of the IEEE Computer and Communications Societies, Mar. 2004, pp. 2446-2457.
[42] QualNet, http://www.scalable-networks.com/.